Centrifugal fan-wheel.



E. B. WILLIAMS. CENTRIFUGAL FAN WHEEL. APPLlCATlON FILED JUNE 25.1914.

1 ,1 54,1 52.. Patented Sept. 21, 1915.

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EUGENE B. WILLIAMS, 0]? BOSTON, MASSACI'IUSETTS, ASSIGNOR T0 B. F.STUETEVANT COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

CENTRIFUGAL FAN-WHEEL.

Specification of Letters Patent.

Patented Sept. 2]., 1915.

Application filed June 25, 1914. Serial No. 847,265.

To all whom it may concern:

Be it known that I, Enenrn B. WILLIAMS, a citizen of the United States,residing at Boston, in the county of Suffolk and State of Massachusetts,have invented certain new and useful Improvements in Centrifugal FanWheels; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

The invention relates to centrifugal fan wheels which take the air inaxially and discharge it circumferentially.

The object of the invention is to provide a fan which will act with highmechanical efficiency when driven at higher speeds than has heretoforebeen found practicable, and which is therefore well adapted for directsteam turbine drive.

To this end the invention consists in the features of construction andcombination of parts hereinafter described and set forth in the claims.

The invention will be readily understood from an inspection of theaccompanying drawings and the following detailed description of the fanwheel illustrated therein.

In the drawings, Figure 1 is a front elevation of a fan embodying theinvention in its preferred form, a part of the fan casing being brokenaway; Fig. 2 is a vertical sectional view on line 22, Fig. 1; Fig. 3 isa detail section on line 33, Fig. 1; and Fig. 4 is a detail view showingone of the fan blades.

As shown, the fan wheel is provided with a central hub 1 by which it issecured to the driving shaft 2. A supporting back disk 3 is secured tothe rear side of the hub, and supports and carries the series of fanblades at. The blades are opened to the inflow of air for most of theirradial depth on the intake side of the wheel, and have their innerperipheral edges 5 inclined or tapered from a maximum diameter at theintake side to a minimum diameter at the back disk. This provides afrusto-conical intake chamber within the blades which allows free accessof air to that part of the wheel nearer the back disk,'as well as tothat part which is near the intake side of the wheel. To enable theWheel to act with high mechanical efficiency when driven at periphery intoward the center.

high speed, the blades are inclined or curved rearwardly with relationto the directionof rotation of the wheel. The blade curvature in a planeperpendicular to the axis of the fan is that of the involute of a circlefor the greater portion of its depth from the outer So long as theinvolute is preserved, a passage between two adjacent blades is providedwhich is of equal or uniform cross-sectional area, with a result thatthe losses due to expansion in the air passage and eddy currents isminimized, and the efliciency thus increased. As the blades approachmore closely to the center of the wheel, the blade curve graduallydeparts from the involute of a circle to a curve or circle of relativelysmall radius. This renders this part of the blade more effective inimpelling the air, and since its speed of movement is relatively verylow at this point, the blade may be thus shaped to act more effectivelyin carrying the air forward than w-ould'be the case were the involutecurve continued to the inner edge of the blade without impairing themechanical efficiency of the wheel. In the construction shown, thecurvature of the blade follows approximately the involute curve tosubstantially the point indicated at 6 in Fig. 1, and here merges with acircle of comparatively short radius, so that the curvature at the innerpoint of the blade is approximately radial of the wheel.

The intake ends of the blades are secured to an annular ring '7, and theblades are strengthened and their form preserved against the centrifugalstrains developed when the wheel is run at exceedingly high speed byannular rings 8 which are set into notches or recesses cut in the outerperipheral edges of the blades. The blades are secured to the rings 8 byangle irons 9 and bolts 10, as indicated in Fig. 3. The rings 8 not onlystrengthen the wheel and maintain the blades in proper shape against thecentrifugal strain, but also tend to equalize the flow of the air fromthe periphery of the wheel along the axial length of the blade.

The wheel is adapted for use in any form of casing, and as shown, ismounted within a casing comprising a rear plate 11 and a front plate 12which is provided with an intake eye 13 registering with the intake ofthe fan wheel.

vVhile it is preferred to employ the specific construction andarrangement of parts shoWn and described, it will be understood thatthis construction and arrangement is not essential to the broaderfeatures of the invention, and may be varied or modified Withoutdeparting therefrom.

Having explained the nature and object of the invention, andspecifically described one form of a fan Wheel in which it may beembodied, What is claimed is l. A centrifugal fan Wheel, having, incombination, a supporting back disk, a series of rearwardly inclinedblades having a curvature Which is approximately the involute of acircle for the greater portion of their depth, and a curvature ofcomparatively small radius at their inner portions and of rearWardlycurved blades having a curvature approximately the involute of a circlefor the greater portion of their depth and which merges With a circle ofcomparatively small radius at the inner portion of the notches formed inthe outer peripheral edges of the blades, and annular rings fittingWithin the notches and secured to the blades.

EUGENE B. WVILLIAMS,

Witnesses: I

' BURTON NV. CARY,

A NIE O. RICHARDSON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

Washington, D. G.

